1. Field of the Invention
The present invention relates to a rechargeable battery and its method of manufacture, and more particularly, the present invention relates to a rechargeable battery having an enhanced lead tab coupling structure and its method of manufacture.
2. Description of the Related Art
Rechargeable batteries can repeatedly charge and discharge due to a reversible transformation between chemical energy and electrical energy thereof. Nickel-cadmium batteries, Nickel-hydrogen batteries, and lithium rechargeable batteries are widely used rechargeable batteries. The lithium rechargeable battery has an operating voltage of 3.6V or more. The operating voltage of the lithium-cadmium battery is three times higher than that of the nickel-cadmium battery or the nickel-hydrogen battery. In addition, the lithium rechargeable battery has a high energy density per unit weight. Therefore, recently, the lithium rechargeable battery has been widely used as a power source for portable electronic apparatuses. The lithium rechargeable battery is classified as a lithium-ion rechargeable battery, a lithium-ion polymer battery, and a lithium polymer battery.
A typical rechargeable battery includes an electrode assembly having an anode, a cathode, and a separator disposed between the anode and the cathode, a case containing the electrode assembly, and a cap assembly coupled to the case to seal the case. The anode and the cathode are provided with respective uncoated anode and cathode parts that are not coated with an activation material. The uncoated anode and cathode parts are disposed in different directions.
The uncoated cathode part is coupled to a cathode collector plate electrically connected to the case, and the uncoated anode part is coupled to an anode collector plate electrically connected to the cap assembly.
The cap assembly and the anode collector plate are connected to each other by a lead tab made of a conductive metal. The lead tab is welded to the cap assembly and the anode collector plate. The lead tab in a bent state is disposed between the cap assembly and the anode collector plate.
However, conventionally, when the lead tab is subject to a bending process, stress is concentrated on a coupling portion of the lead tab and the cap assembly. Therefore, the coupling portion may be damaged. Accordingly, the damage may cause degradation in performance of the rechargeable battery. Moreover, if the coupling portion is broken, the anode and the cap assembly are electrically disconnected, so that the rechargeable battery cannot function.